If $A=\left[\begin{array}{ccc}a & c & -1 \\ b & 0 & 5 \\ 1 & -5 & 0\end{array}\right]$ is a skew-symmetric matrix, then the value of $2 a-(b+c)$ is

If $\left[\begin{array}{lll}x & 2 & 0\end{array}\right]\left[\begin{array}{c}5 \\ -1 \\ x\end{array}\right]=\left[\begin{array}{ll}3 & 1\end{array}\right]\left[\begin{array}{c}-2 \\ x\end{array}\right]$, then value of $x$ is

Find the matrix $\mathrm{A}^2$, where $A=\left[a_{i j}\right]$ is a $2 \times 2$ matrix whose elements are given by $a_{i j}=$ maximum $(i, j)-$ minimum $(i, j)$

If for a square matrix $$\mathrm{A}, A^2-A+I=\mathrm{O}$$, then $$\mathrm{A}^{-1}$$ equals: